Endurance Sport Science and Triathlon Tips

Researchers in Canada recently did a review of research on acupuncture, looking at whether it can help treat musculoskeletal injuries of the extremities.

They did a systematic review of scientific studies, and found that many acupuncture studies were likely to be biased and unreliable.  Using the studies that were reliable and objective, they concluded that acupuncture may give some relief for carpal tunnel syndrome or achilles tendonitis; and electro-acupuncture may provide some relief for shoulder injuries.  However, there is very little scientific evidence that acupuncture provides specific benefits in treating injuries, beyond the placebo effect.

We don't think this means you should avoid acupuncture, but you should be realistic that, so far, there is little scientific evidence of its effectiveness for sports injuries.

Scientists recently conducted a randomized controlled study of ultramarathoners who completed the Western States Endurance Run, to determine if either massage or pneumatic compression, used after the race, improved their recovery from the race.  The race is a 161-km (100-mile) endurance race.  Runners were tested before and after the race for function (400 meter running speed), as well as subjective pain and fatigue.  One group of runners received massage for 20 minutes after the run; a second group received pneumatic compression; a third control group simply lay supine after the race.

The conclusion: although runners who received massage and compression subjectively reported a little less pain and fatigue right after treatment, there was NO difference in function, fatigue, or pain in the days following.  In other words, it appears that any effects of massage or pneumatic compression were due to placebo effects, not physiological benefits.

It's certainly okay to utilize these techniques if it makes you "feel" better; but you should also realize they appear to be fairly ineffective in significantly changing muscle recovery after a gruelling endurance event.

Recently, some endurance coaches have begun to tout the benefits of "training low," i.e. training with limited carbohydrate nutrition, in an effort to force the body to utilize more fats for energy and thereby extend endurance.  However, there has been very little research on this subject.  One of the negative consequences of training without carbohydrates is the possible reduction in power/energy during training sessions, which can make it difficult or impossible to train at high intensities.  In other words, your body may use more fat for energy -- but may also be unable to achieve the speed/power needed to improve performance.

A new study has attempted to find a solution to this problem, while also measuring the performance benefits of the low-carbohydrate training strategy.  Essentially, researchers allowed endurance athletes to consume carbohydrates BEFORE high-intensity training sessions, to ensure they had enough muscle glycogen (energy stores) to achieve their session goals; then restricted carbohydrate intake during and AFTER the high-intensity session, including overnight and into the next morning's low-intensity training session.  They compared results from this group to results from an equivalent group who did not restrict carbohydrate intake at any time.  The results were startling: in just 3 weeks of the "train-high sleep-low" program, athletes in the experimental group improved performance (in running and cycling) significantly more than the control group -- and also significantly reduced body fat/weight.

These findings are intriguing, although far from definitive.  These were small groups of athletes, following the program for only 3 weeks.  We believe it MAY be beneficial for advanced athletes to experiment with this type of program, but ideally under the supervision of a coach or nutrition professional.  Proper hydration, calorie intake, and other nutrients must be maintained even while somewhat restricting carbohydrates; and the restrictions must follow a strict schedule.  We also don't know the effects of following such a program for LONGER than 3 weeks.

Maintaining protein balance appears to be essential for athletes, in order to maintain, replace, or grow muscle tissue.  Training, especially strength training, causes damage to muscle tissue.  After training, the muscles repair themselves and build new tissue to be ready for future challenges.  If training is sufficiently intense, the muscles add tissue to grow larger and stronger.  Muscle tissue is made largely of proteins, so you must eat sufficient quantities of protein to supply your muscles with the building blocks of repair and growth.  It appears that most athletes need about 1.3-2.0 grams of protein PER KILOGRAM OF BODY WEIGHT per day.  For example, if you weigh 220 pounds, you weigh 100 KILOGRAMS; therefore, you need about 130-200 grams of protein per day.  Taking significantly more protein will NOT improve results or build any more muscle.

After training sessions, it appears that your muscles are ready to absorb protein and rebuild for up to 24 hours: it is not necessary to follow training sessions with an immediate protein shake or high-protein meal.  In general, animal sources contain richer protein, with greater amounts of the essential amino acids: it may require more vegetable protein intake to achieve good protein balance during training.  It appears that the amino acids leucine and arginine may be the most essential for muscle recovery and building.  Make sure your protein sources are rich in those amino acids.

Although there is no need for protein supplementation, as long your diet includes enough high quality proteins, there is also nothing wrong with supplementation if it helps you achieve protein balance.

There is still no evidence that protein is required during athletic training or competition, or that it improves performance or endurance.  On the other hand, there is still significant research showing that carbohydrate intake can improve performance during endurance events.

Researchers have taken new looks at the effectiveness of drinking cold liquids (or ice slurries) during endurance exercise.  Recent studies are pointed toward extremely cold liquids causing a NEGATIVE net effect on body heat, as apparently the gut pulls heat INTO the core of the body to neutralize the cold temperature of the ingested liquid.  In other words, there may be NO benefit, and possibly INCREASED overall body heat, when drinking such cold liquids.  Although research is still limited, we believe a prudent approach is to make no effort to drink hyper-cold liquids during training or racing.  However, dehydration itself is still a high risk in warm/hot conditions: don't avoid drinking cold liquids if those are your only option.  Just avoid chilling your drinks: let them be as warm as the air temperature (even if it doesn't seem as refreshing) for optimum body temperature regulation.

Recent research on plyometric training indicates that, in as short a time as six weeks, it can improve your running speed and economy, even for endurance running.

Experimental subjects who engaged in plyometric training in addition to their regular run training, improved their 3 km time trial speeds and achieved better running economy, i.e. used less energy for the same speed. Although this research didn't cover longer distance running, we believe it adds to the evidence that strength training is of benefit to runners and endurance athletes.  Plyometric training is a specific type of strength training, which involves jumping,  rapid changes of direction and high forces.  You must approach such exercise gradually, and we recommend seeing a qualified trainer to develop a program.

Researchers in physical therapy recently described a new exercise being used to help heal and prevent upper hamstring tendonitis (chronic pain) in runners.  We have seen many runners and triathletes with this kind of chronic or recurring injury.  In general, eccentric strengthening of the hamstring muscles works pretty well in such cases.  Eccentric strength exercises involve pushing against resistance while the muscle is lengthening (rather than shortening): a typical example with hamstrings would be reverse leg curls -- lifting a weight with both legs, then lowering it slowly with the injured legs.  In a case that didn't respond to those traditional exercises, the researchers added reverse resistance on a treadmill: standing facing away from the console, with one leg on the side rail, the patient resisted the belt's movement with the injured leg at 0.5 mph.  Within a few weeks, the runner had complete relief from the pain, and was able to gradually resume running without reinjury for a year afterward.

The new seatpost from Redshift Sports has revolutionized triathlon for cyclists who have (or prefer) a road bike, rather than a TT bike.  The seatpost actually flips back and forth from road-optimal to aerobar-optimal riding positions, even during a ride.  Now you can add aerobars to your road bike without compromise good biomechanics or causing back/hip pain and injury.  Redshift has also developed aerobars which easily clip on and off your road handlebar, so you can easily attach them any day you want to use them; and they can also be fitted with an aerobar bottle cage which detaches with the aerobars -- smart!! See us for these modificationRedshift seatposts!

A new research study of cyclists looked at time trial performance in hot weather conditions, as well as acclimatization.  Researchers compared performance on the first day in hot weather, with performance after 6 days and 14 days in the heat.  On the first day, performance was significantly decreased, with power outputs dropping later in the (43k) time trial; on the sixth day, performance was still somewhat decreased, though better than on day one; on the 14th day, performance had returned to the same level as performance in cool conditions.  Although this study included a small number of athletes in a relatively short time trial, it suggest that full acclimatization may take as long as two weeks in the heat.  If you have hot-weather races on your calendar - especially if travelling from cooler weather - be aware that your performance may be affected if you haven't taken the time to acclimatize.

Researchers recently studied runners' trunk positions (the amount of forward lean) during running, to setermine what effect it has on running mechanics.  They discovered a pattern, whereby those who run with more forward flexion (lean), use their hip muscles more, but do less work and absorb less shock with the knee extensor (quadriceps) muscles.  This jives with our empirical findings that a good forward lean tends to reduce knee impact.  At Sportfit Lab, our Running Gait Analysis can measure your trunk flexion and then we can help you work on your form to reduce the risk of knee injuries.

Recent research, along with findings from our Lab, call into question the benefits of switching to "minimalist" or "barefoot" shoes.  Barefoot shoes, such as Vibram Five Fingers, are considered to be those which simply cover the foot, but provide no significant cushioning nor support.  They usually have separate compartments for each toe. Minimalist shoes are generally shaped more like traditional running shoes, but are extremely light in weight, with very little support either inside or outside the shoes.  Some have lightweight cushioning in the midsole, but most provide little (if any) arch support, and many place the heel lower ("zero drop") than do traditional running shoes, with significantly less cushioning under the heel.

Minimalist shoes have been touted as a way to force, or at least encourage, the runner to adopt a more "natural" running motion, and/or to convert from heel-striking to mid- or forefoot striking.  However, the research conducted so far does NOT support those claims.  First, there is no specific evidence that humans are meant to be forefoot strikers when we run.  Indeed, many successful distance runners - and the majority of runners at most running events - are heel strikers.

Most importantly, several studies have shown that changing to minimalist (or barefoot) footwear does NOT cause the wearer to adopt a different -- or less heel-striking -- running style.  It appears that only deliberate practice can produce a change in running form.

So, is there any advantage to wearing minimalist shoes?  Interestingly, there is some evidence that their lighter weight may slightly reduce the energy needed to run long distances, resulting in better endurance or speed.  Does that mean you should switch to minimalist shoes to go faster?  ABSOLUTELY NOT!  As with cycling, comfort and injury prevention are more important that slight savings in weight: there's no point going a little faster if it causes you to wind up with injuries.  In addition, there are now well-cushioned shoes available which are extremely light in weight, too.

If minimalist shoes don't change your running style, should you try to change your running style anyway?  The answer is: very possibly.  While minimalist shoes won't change your form, adopting a higher cadence (170-180 steps/min.), leaning forward at the torso, and landing with your feet more underneath your body (as opposed to out in front) will reduce your landing impact, improve your economy of motion, and gradual increase your potential speed -- no matter where on your foot you land.  Often, that improved form WILL cause you to shift your landing to more midfoot/forefoot, however.

So, who should (or shouldn't) use minimalist shoes -- and which ones are best?  Our video analysis of hundreds of runners, indicates that those with light body weight, good arch/ankle stability, and who already strike on the mid- or forefoot, are the best candidates to try lighter-weight or minimalist shoes.  Heavier runners, and those with flat or overpronating feet, are likely to need more support than is provided by the minimalist shoes.  We also see some differences among brands and models of minimalist shoes.  The best seem to provide SOME support and stability for the foot.  The worst, such as many of the original Newton shoes, may be worse than barefoot running, because they cause the foot to be completely unstable -- and work much harder -- when it strikes the ground.

If you do decide to try minimalist shoes, it is EXTREMELY IMPORTANT to follow these guidelines:

1. Before running in them, start by walking a few hours a day in them.  Because of the low heels, you may feel stretching in your calves and/or Achilles tendons.
2. Once your feet and lower legs have adjusted, use the shoes only for short runs initially.  Increase mileage VERY gradually, making sure you have no pain afterwards.
3. Do extra stretching for your calves/Achilles to prevent overstretching or injuring those muscles.
4. If you do develop unusual aches or pains, get them evaluated immediately.

At SPORTFIT LAB, we can do a running/gait analysis to help determine if you are a good candidate to try minimalist shoes.  If not, we can recommend what type of shoes are most appropriate for your foot type and running form.

Recent stories of endurance athletes suffering from hyponatraemia -- and some even dying -- have raised awareness of this acute illness. Hyponatraemia is an imbalance in your body's internal fluids, in which your internal sodium concentration drops too low.  Symptoms can include nausea, dizziness, fagigue, vomiting, headache, and confusion.  It has been hypothesized that drinking too much water during endurance events could cause exercise-related hyponatraemia.  In fact, some coaches and sports scientists have been recommending less hydration during endurance exercise, apparently due to fear of hyponatraemia.

However, the most current research casts doubt on that hypothesis: so far, there has been no causal link proven, between amount of drinking (or what you drink) during an exercise or race and hyponatraemia.  It is clear that this syndrome is not well understood.  Our review of current research suggests that significant dehydration is well established as a cause of reduced performance.  Elite triathletes are shown to sweat at a rate of about 1.8 liters/hour (males) and 1.3 liters/hour (females).  Some dehydration during exercise/racing is harmless.  However, we believe that a sound recommendation is to drink at least 12-16 ounces of liquid per hour, during any endurance event longer than one hour, and during which you are sweating.  Drink more if thirst dictates.  Research indicates that a solution (or sports drink) with electrolytes and carbohydrates is likely (but not guaranteed) to give the best results and maintain your performance.

Researchers in the UK and Netherlands recently studied the effects of self-talk on endurance performance.  In a well-designed study, cyclists were instructed to repeat specific messages, to themselves, during a time trial done to exhaustion.  Results showed that cyclists who repeated positive, motivational messages (e.g., "feeling good" or "push through this") to themselves, actually performed better -- they were able to ride longer, and perceived lower exertion effort -- than those who did not.

Although it makes sense that positive thinking can influence performance, there is increasing evidence that self-talk can be used as a training technique.  Just as you train your body to perform, you can train your mind as well.  In this study, cyclists were actually trained within a few weeks to practice and then employ specific examples of positive self-talk.  So, don't forget to use your MIND as the #1 performance-booster.  [MSSE]

Researchers looked at all the studies done, so far, on compression clothing and sports performance.  Although differences were small, and it's hard to dismiss the possible placebo effect, it appears that compression garments help to improve power and endurance slightly.  They also appear to produce some beneficial effects in speeding up recovery AFTER workouts.  We're not sure if this effect is significant -- or all physical -- but we do know that compression garments feel great.  We offer a range of compression products at the Lab, from CW-X, Louis Garneau, and Zensah.

Scientists compared two training programs in trained cyclists: one consisted of low-intensity endurance training and steady, moderate intensity "threshold" training; the other consisted of some low-intensity endurance training alternated with high-intensity interval training.  The high-low intensity program produced better results (in power and endurance) -- in less training hours per week -- than the low-moderate intensity program.  It appears, from this and other studies, that high-intensity training is critical to maximum improvement in athletes -- and can save training time as well!

European researchers looked at the effect of taking salt with water, vs. water only, on cycling performance in hot conditions.  10 cyclists performed exhausting time trials after drinking plain water, or water plus salt.  Although the numbers are small, the test showed distinct improvements in performance with salt ingestion.  Interestingly, the salt ingestion didn't lower body temperature or reduce sweating; but it did maintain cardiac output and result in better time trial performance.  This presents further evidence that sports drinks with electrolytes may be better than plain water.

Researchers at James Madison University tested three types of recovery nutrition after exercise, by measuring glycogen levels and having subjects perform a time trial four hours after exhausting exercise.  One test used only carbohydrates; one used carbohydrates with a small amount of protein; and one used mostly protein with very little carbohydrate.  The results: although carbohydrates raised blood glucose and insulin levels more than protein, no differences were found in any meaningful indication of recovery - including subsequent exercise.  It appears, from this study, that calories are more important than the exact composition of recovery formulae.

Two more studies have linked hip strength -- in the abductor (outer hip) and gluteal (buttocks) muscles -- with good running mechanics.  One study measured hip position in hundreds of runners, then follwed them to see which runners would develop knee pain.  Those who did develop knee pain, had been running with significantly more hip adduction, which is usually caused by weak hip abductor muscles.

In the second study, researchers looked at the running form of collegiate cross-country runners. Those with weaker hip muscles were more likely to run with excessive torso and pelvic motion. Interestingly, hip abductor weakness was more prevalent in the femalr runners. 

Researchers at North Dakota State U. tried to determine if moderate or severe dehydration cause an increased risk of muscle cramps -- a vexing problem for many athletes.  In their study, they had young athletes exercise until they were dehydrated and had lost significant amounts of electrolytes.  They then measured the susceptibility of a specific muscle to cramping when artificially stimulated to contract.  They found no correlation between dehydration and muscle susceptibility.  Although this study was very limited -- it only used young athletes and artificially-induced muscle contractions -- it provides more evidence that cramping may be more related to muscle fatigue and other factors, rather than dehydration or electrolyte loss.

In cyclists, we have found that cramping is often a function of biomechanical issues linked to position (or fit) on the bike.  If one muscle (or muscle group) is overactive due to poor positioning, it will fatigue before other muscles -- and sometimes cramp as a defense mechanism.  If you have significant cramping issues while cycling, it would be wise to have your bike position -- including shoes, cleats, etc. -- checked by a qualified fitter. 

Researchers from Norway and Denmark looked at the effects of heavy strength training on cycling power.  Highly-trained cyclists were separated into a control group (regular endurance cycle training) and an experimental group (endurance training plus heavy strength training twice a week).  The strength-training group saw significant gains in cycling power AND endurance over a 12 week period.

Contrary to some long-held beliefs, heavy strength training does not appear to hinder endurance training.  Also, note that only 2 strength workouts a week were sufficient to see improvements, although they were certainly intense workouts.

Recent studies had added data to the arguments over barefoot running.  Is barefoot (or "minimalist") running beneficial?  Is that style of running -- mid-foot or forefoot landing -- better than heel landing?  Were we meant to run barefoot or to land on our forefeet?  In one study, researchers looked at the relative energy used in barefoot running vs. shod running, and found that barefoot running (with forefoot landing) required less energy and seemed to reduce impact.  However, this study may have been flawed for 3 reasons: (1) the subjects used were runners already accustomed to running barefoot; (2) researchers did not control for the additional weight of running shoes; and (3) the research-ers themselves are promoters of barefoot running in the media.

More recently, a different study looked at energy differences between barefoot and shod running, also in runners accustomed to barefoot running.  But, in this study, the researchers accounted for the weight differences in footwear -- and even added weights to barefoot runners as a comparison. The results were enlightening: the weight of running shoes added significant, if small, energy cost to running -- which accounted for all of the differences in energy costs between trials.  In fact, after subtracting the weight of footwear, running with shoes was slightly MORE efficient than running barefoot.  Although this was a small study, researchers had to conclude that running with lightweight shoes is just as efficient as running barefoot.

Keep in mind that these studies looked only at running efficiency, not injury risk or rates of injury in running -- just the energy expenditure.

Researchers attempted to determine if drinking a diluted sports drink would have the same benefits during endurance racing, as drinking "full-strength" sports drinks.  Most endurance sports drinks have about 6-8% carbohydrate in solution. Most studies have shown a positive benefit from using such drinks, i.e. better endurance.  In this study, researchers used 0% (plain water), 2%, 4%, and 6% solutions, measuring time to exhaustion at exercise levels equivalent to endurance racing (resulting in exhaustion in about 2 hours).  Results showed that the higher the carbohydrate levels, the better the performance.  It appears from this (limited) study, that sports drink manufacturers have found an effective formula at 6-8% carbohydrate.  Of course, using gels, bars, or other carbohydrate sources -- along with water or diluted sports drink -- could have the same beneficial effects as full strength sports drinks used alone.

A pair of studies published in Medicine and Science in Sports and Exercise demonstrate the powerful effect exercise can have on brain health and psychological symptoms.  In the first study, researchers looked at over 14,000 people for an average of 17 years.  Greater cardiovascular fitness (as measrued by peak oxygen uptake) was negatively associated with risk for Alzheimers and death from demential.  The greatest percentage gains were seen between unfit (sedentary) people and those of moderate fitness.  The conclusion: even moderate fitness helps protect us from developing brain diseases later in life.

The second study focused on symptoms of depression in men, versus exercise participation.  In general, those who exercised more had the lowest rates of depression.  Again, the greatest gains were between the least active group and those exercising moderately: high levels of exercise didn't significantly add to the protective effect in most (but not all) cases.

Researchers in Europe tried to find causes for gastrointestinal symptoms in endurance athletes.  They studied participants in Ironman, half-IM, and cycling stage races to correlate food intake with GI distress.  However, there was no consistent pattern found -- except that athletes with a history of GI distress continue to suffer from the problem.  Researchers saw some weak correlation between higher carbohydrate intake and two mild symptoms, flatulence and nausea; but no correlation with more serious symptoms.  At the same time, higher carbohydrate intake also correlated with better race performance.

Researchers from Australia and France carefully timed competitors in the 2009 European Triathlon Championships, to determine the success of various pacing strategies during the 10K run portion of the race.  These were elite competitors, yet most started the run -- the first of four 2.5K laps -- at a fast pace, then gradually slowed in the subsequent three laps.  The most successful runners were those who both (a) reduced their speed the least over the four laps, and (b) maintained the steadiest pace over hills [each lap had one hill climb].  Males were able to maintain their pace better over hills, which led to faster overall times than for females.  It would appear that "starting too fast" is a risk, at least in elite triathletes, which can lead to reduced speed later in the race and worse overall performance.  Moreover, this provides more evidence that keeping a steadier pace -- by working harder over hills or through headwinds, then easier on descents or through tailwinds -- may be more advantageous than the reverse. [JISPP June 2011]

Brazilian researchers recently looked at the effects of aerobic training on asthma symptoms.  They found that aerobic training significantly reduced airway inflammation in patients with moderate or severe asthma, "and these benefits were more significant in subjects with higher levels of inflammation."  It appears that aerobic training should be seen as therapeutic for asthmatics, not harmful.

The recent trend toward barefoot or "minimalist" running -- running with little or no footwear -- has taken the running world by storm.  Virtually every shoe manufacturer is now offering minimalist shoes which provide little more than a covering for the foot -- no significant cushioning nor support.  As with most new trends, the media are replete with success stories of runners who have switched to minimalist shoes and "cured" a wide range of running ailments and injuries.  Unfortunately, anecdotes don't make for good science...many sports and nutrition fads have come and gone after being proven to offer no more than a placebo effect -- or to have greater risks than benefits.

So what does the science say about minimalist running?  First, there is no definitive evidence that primitive humans were significantly more successful at distance running than modern humans.  The current existence of an indian tribe in Mexico which is full of distance runners who run in sandals, does not prove that such running would be beneficial for everyone.  Second, forefoot landing -- the running technique which barefoot running is purported to force you into adopting -- is not necessarily more successful than any other technique.  Research indicates that successful distance runners include runners with many different styles, including heel-strikers and midfoot landers.

The jury is still out, as to whether changing to barefoot/minimalist shoes will have positive or negative effects -- or different effects in different people.  Already, numerous reports of injuries directly related to adoption of these shoes are coming in.  We have, ourselves, worked with several athletes who suffered foot or lower leg injuries soon after changing to minimalist shoes.  Until good science shows specific benefits, we cannot recommend minimalist footwear to all runners.  We remain open-minded, but we caution runners who want to try minimalist running:

1. Primitive humans did not run on asphalt; if you do, you will suffer more impact than those ancient runners did.

2. If you've grown up, and learned to run, with supportive shoes, then your feet and body have adapted to that.  It will take many months -- possibly years -- for your feet and body to re-adapt to an entirely different running posture.  If you want to try it, start by walking short distances in minimalist shoes; then, very gradually increase the time you spend in them; finally, start jogging/running short distances before attempting longer runs.  If you're not willing to gradually adapt, you may be risking injuries.

3. It's probable that some runners simply don't have the foot/leg structure to run successfully without good arch support or cushioning.  Again: if you decide to try changing, do so VERY gradually and be alert for signs of injury.  A good foot/leg evaluation may also help evaluate your situation before trying to switch.

Researchers recently measured the energy cost and muscle actions of deep-water running, the kind usually done with a flotation belt or vest.  Many doctors, physical therapists, and trainers recommend water running as a safer alternative to land-based running -- especially useful for rehabilitation from injuries.  Scientists have now measured its effectiveness, finding that water running can certainly provide a good cardiovascular workout, although the energy used is somewhat less than land running at the same perceived exertion (subjective intensity level).  Hip and thigh muscles are highly active during water running; but lower leg muscles are much less active than in land running.  Our take: if you're suffering from foot, ankle, or lower leg injuries, water running is a great substitute for land running during rehabilitation, but won't specifically strengthen the lower leg muscles.  For upper leg, hip, or groin injuries: water running may be too strenuous in early rehabilitation, but can help strengthen those muscles with controlled therapy.

Researchers at the University of Wisconsin examined different stride rates in runners, to determine the relative stress to knee and hip joints. Results showed that increases in stride rate (a.k.a. "turnover") reduced the impact forces on the knee joints of runners. Large increases in stride rate also reduced forces and motions on the hip joints. Runners started at their preferred stride rates (and speeds), then were instructed to increase or decrease stride rates by 5% and 10%. In all cases, faster stride rates - which resulted in shorter stride LENGTHS - were associated with reductions in impact forces. Interestingly, most of the runners showed slight increases in perceived exertion at the higher stride rates; in other words, it felt more difficult for them to achieve the higher stride rates. The study did not assess long-term changes in running style, but we would hypothesize that, once runners became accustomed to the faster stride rates, their perceived exertion would fall back to original levels. Indeed, we have seen this occur in our training of runners. Based on other research into elite runners and running economy, we can say that a stride rate of about 180 steps per minute is a good goal for most runners, combining economical motion with reduced impact (and reduced risk of injury). Many recreational runners use slower stride rates, putting their joints at increased risk of impact injuries. If you decide to increase your rate, make the change gradually - it will probably take several months to become accustomed to a significantly faster stride rate.

Norwegian researchers examined the Gross Efficiency of cycling, considered a good measure of overall cycling performance.  In the past, it's been hypothesized that Force Effectiveness - the ability to exert maximum force perpendicular to the crank arm - might be the best correlate with Gross Efficiency.  In other words, it was thought that more forceful pedaling - particularly during the "effective" downstroke - would correlate well with Gross Efficiency.  However, these researchers measured "Dead Center," essentially the ability to maintain force at the top and bottom of the pedal stroke vs. the middle of the stroke.  They found, in elite cyclists, that "Dead Center" - essentially the smoothness or consistency of the stroke - was highly correlated with Gross Efficiency, i.e.  smoother pedaling took less energy.  If corroborated by more studies, this finding would indicate that the Computrainer "SpinScan" we use to provide a measure of that smoothness, is an excellent predictor of cycling performance.  We can also hypothesize that triathletes - who ride relatively smooth courses and must follow with a run - would need this kind of pedaling even more than cyclists.  We also don't know yet if changes in crank length would change the equation and affect the Gross Efficiency.  Stay tuned for further research...and work on a reasonably smooth pedaling stroke for triathlon.  [MSSE 43:4]

Researchers in Canada recently compared the effects of sprint interval training (SIT) with slow endurance training (ET) over six weeks of training.  Both groups ran on treadmills for exercise.  The ET group did 3 sessions per week of 30-60 minutes each, at 65% of VO2max.  The SIT group did 4-6 sprints of 30 seconds each with about 4 minutes of recovery between sprints, also 3 times/week.  Surprisingly, both groups showed similar improvements in VO2max and similar body fat reductions over 6 weeks.  It would appear that sprint interval training may be a viable way to improve fitness with less time involvement than endurance training.  However, here are a few cautionary notes: (1)  The study was done on young adults; although SIT proved fun for these youngsters and didn't cause any injuries, older adults may not respond as well to SIT.  (2) Although VO2max improved similarly in both groups, cardiac output DID NOT.  Only ET produce positive changes in cardiac output, so it appears the VO2max improvement in SIT runners was due more to musclular improvement than cardiac improvement; thus, SIT may not result in the same cardiovascular health benefits as ET...although longer trials may tell more.  (3) The trial was on a limited number of participants and over a fairly short term; we await confirmation of the benefits shown here, as well as extension of such trials to larger population groups and/or over longer time periods.  For more details:

 http://www.multibriefs.com/briefs/acsm/active1-25.htm

Brazilian researchers recently looked at the effects of aerobic training on asthma symptoms.  They found that aerobic training significantly reduced airway inflammation in patients with moderate or severe asthma, "and these benefits were more significant in subjects with higher levels of inflammation."  It appears that aerobic training should be seen as therapeutic for asthmatics, not harmful.

It has long been assumed, with only a little corroborative research, that dehydration and electrolyte loss were the chief culprits in muscle cramping.  Recently, researchers performed a study of muscle cramping, looking at the threshold of electrical stimulation that would cause cramping.  They found that 30 minutes of cycling performed in hot conditions did cause dehydration, but did NOT decrease the threshold for cramping.  Although this is a very limited study, it suggests [albeit weakly] that fatigue may play a larger role in cramping than previously thought, compared with dehydration or loss of electrolytes. [MSSE 42:11]

Researchers in Europe recently compared carbohydrate utilization during endurance (180-minute) cycling in eight trained cyclists.  Results of the study showed that carbohydrate usage was similar for carbohydrate liquids, gels, and solid bars.  Although the number of subjects was small, and the type of carbohydrates (e.g. glucose, fructose) in the formulae varied slightly, the results were fairly consistent.  We feel this provides some additional evidence that your choice of carbohydrate can be based on your preference, without worrying about which type of substance will deliver "better" carbohydrate supplementation during cycling.  [MSSE 42:11]

In another study on this subject, researchers in England examined the effects of ingesting carbohydrates WITH protein during long/challenging cycling workouts.  Comparing the effects with ingesting carbohydrates ALONE, researchers found NO added benefit to adding protein.  Of course, it's well proven that carbohydrates can increase endurance and reduce fatigue.  Although some sports-drink companies market carb-protein combination drinks as being superior, there is currently no scientific evidence to support that claim. [MSSE 42:6]

Recently, some sports nutritionists - even from USA Triathlon - have been promoting the concept of training the body to utilize fat, rather than carbohydrates, during endurance exercise.  Their assumption is that the use of more fat for energy will provide performance and endurance benefits during racing.  However, research has not yet confirmed this hypothesis.

     In a new study, British researchers looked at energy usage in fourteen well-trained cyclists.  Their goal was to determine if three weeks of controlled training could affect carbohydrate vs. fat utilization - and if either condition would provide an advantage.  Half the cyclists trained daily and alternated moderate-intensity aerobic training every second day with high-intensity interval training every other day.  This would allow muscle glycogen stores to be replenished between workouts.  The other half of the group trained only every second day, but performed both workouts (aerobic and interval) on the same day - so that interval training would be performed with depleted muscle glycogen.  Not surprisingly, the second (glycogen-depleted) group had more trouble during interval training and did their intervals at much lower intensities.   However, three interesting results emerged after only 3 weeks of such training:

(1) Fat usage in the glycogen-depleted group was significantly greater than in the other group during a one-hour time trial.

(2) Despite the lower intensities during (interval) training, the glycogen-depleted group - using more fat - performed just as well on the time trial.

(3) Although the glycogen depleted group used more fat (and less CHO) during the time trial, performance was no better.

     This raises additional questions, yet to be answered by definitive research.  Although it appears you CAN change your energy metabolism through training - perhaps fairly quickly - we don't know the long-term effects of such a change.  We also don't know if the use of more fat for energy would provide any significant advantage over longer races than the one-hour time trial done here.  These researchers speculate that glycogen depletion in training provided some kind of "stress" which made up for the loss of intensity in this training protocol.  More extensive conclusions must await more research. [MSSE 42:11]

Scientists at Appalachian State University recently conducted tests comparing mulitfrequency biolectrical impedance with hydrostatic weighing (considered among the most accurate methods of body composition testing).  Results on wrestlers showed good correlation and accuracy.  We welcome this further endorsement of our InBody testing apparatus for measuring body composition.

Researchers in England used sophisticated force-measuring devices to quantify the forces produced by elite cyclists throughout the pedaling motion.  It was discovered that, in general, about 85% of the work done during pedaling is done during the DOWNSTROKE, with about 15% of the work done in the UPSTROKE.  This provides some evidence that efficiency can be improved BOTH through the pushing and "pulling" phases of the cycle.  However, we would remind triathletes that the pulling muscles - hip flexors and hamstrings - are also needed for running, so it may be more advantageous to use the pushing muscles (quadriceps and gluteals) a little more than cyclists would.  THIS IS A GREAT STUDY WHICH VALIDATES OUR USE OF COMPUTRAINER SPINSCAN data to measure your force output throughout the stroke for each leg.  [MSSE 42:6]

Researchers recently tested the affects of hip abductor fatigue on stability of the knee joint.  The abductors are the muscles (primarily the gluteus medius) on the outside of the hip, which pull your leg outward - or do a "side leg raise" when lying on your side.  These muscles are critical for stability in walking, running, or any other weight-bearing activity.  It has been previously shown that in elderly people who suffer from "shuffling" or swaying side to side when walking, the cause is often weakness of the abductor muscles.  The current study examined younger, athletic people, and found that FATIGUE in the hip abductors causes the knee joint to be less (laterally) stable when landing on one foot (as in running).  Lateral instability puts more pressure on knee ligaments and may increase the risk for knee injuries.  The takeaway message here: even if you participate in "forward motion" sports such as triathlon, building strength and endurance in the hip abductors can help stabilize the knees and possibly reduce your risk of injuries. [MSSE 42:3]

Exercising in hot conditions has always been a challenge for competitive athletes.  As the body's core temperature rises, circulation is compromised, muscle efficiency decreases, and serious injury - such as heat stroke - can occur.  Recently, researchers tested a novel idea for combating heat: PRE-COOLING.  Bike racers tried cooling their legs in cold water for 20 minutes prior to racing a 40-minute time trial in hot (about 85 degrees) conditions.  Compared to trials done without pre-cooling, performances were improved.  However, we must interpret these results with caution: the experiment was not blinded, as riders obviously knew when they were cooling - which may have led to a placebo effect.  Moreover, the researchers could not explain the improved results physiologically, as the greatest improvement seemed to occur after the cooling effects had worn off, i.e. the last 20 minutes of the time trial.  We would say: significant research has shown - in many ways - that keeping cool in hot weather is a high priority for both health and performance.  HOW best to keep cool is still unknown...and perhaps a matter of personal trial and error.  [MSSE 42:3]

Researchers at the University of Queensland in Australia published a study of triathletes designed to determine whether running immediately after cycling - as in triathlon - has a "neuromuscular control" effect on running biomechanics.  They also wanted to discover whether any such effect is related to leg injuries in triathletes.  The researchers studied 34 highly trained triathletes, some of whom had suffered past lower body overuse injuries.  Testing consisted of comparing running performance [without prior cycling] with "running off the bike" performance.  Indeed, some - but not all - of these successful triathletes showed altered muscle patterns (unrelated to fatigue) when running after cycling.  Moreover, this was more likely to occur in triathletes with a history of overuse injuries.  Although the evidence is only circumstantial, it appears that at least some triathletes have trouble maintaining normal running form immediately after cycling - and this may increase the risk of injury.  One possible conclusion: it may raise the risk of injury to engage in frequent or long "brick" workouts, unless you're one of those gifted individuals who can maintain your "normal" running form.

The takeaway message: we recommend doing your heaviest training with independent running and cycling workouts.  Save your brick training for shorter workouts, when you can concentrate on good running mechanics.

In an effort to quantify the risk of lower leg stress fractures, researchers from Trinity U. in Ireland and Iowa State U. studied 10 male runners during running.  Using force data and computer modeling, the researchers determined that increased stride length significantly increases the forces on the lower leg, presumably raising the risk for stress fracture.  In addition - not surprisingly - increases in running mileage added to bone stress.  Although this study (also published in MSSE) has limitations - it doesn't really tell us what causes a stress fracture in any particular runner - it does make clear the added stress on the lower limbs from increasing stride length.  From a practical standpoint, we would simply say that shorter stride lengths may be somewhat safer than longer ones.

A number of popular nutrition supplements include Quercetin, a plant flavonoid, as a chief ingredient.  Manufacturers tout the benefits of this antioxidant for health and athletic performance.  However, most studies - especially with trained athletes - have so far failed to demontrate any significant performance improvements after Quercetin supplementation.  A new study looked at 2 weeks of Quercetin supplementation in untrained males.  Results showed slight but insignificant improvements in endurance performance.  Researchers speculate that Quercetin may help untrained individuals more than athletes; may take longer to show significant benefits; or may really have very little effect on performance at all.

Publishing in Medicine and Science in Sports and Exercise, the research journal of ACSM, scientists demonstrated improved running endurance performance through the ingestion of Spirulina.  Spirulina is a supplement made from a specific genus of bacteria, which contains high levels of protein, essential fatty acids, vitamins, minerals, and photosynthetic pigments.  Health benefits have been claimed for decades, but little controlled research has been done.  In this controlled, double-blind study, runners ingested either Spirulina or placebo for 4 weeks, then reversed treatments several weeks later.  For each condition, runners completed a 2-hour endurance run, then a short high-intensity run to exhaustion.  After Spirulina supplementation, runners showed a tendency to burn a higher percentage of fat and lower percentage of carbohydrates during the 2-hour run.  They also lasted longer during the high-intensity run.  It is not known specifically why Spirulina would cause such effects. Although a well-controlled study, this research involved a small number of runners.  We would stop short of recommending Spirulina for all runners - yet.  But we will be watching for additional research on this intriguing supplement.

Australian researchers recently studied male distance runners to determine speeds and pacing strategies in running a 9.5-km course with three significant hill sections.  Each uphill and downhill section was preceded by a level section - hills were essentially plateaus.  Speed and oxygen consumption were measured on each section of the course, to determine runners' self-selected strategies for running uphill, downhill, and level.  As expected, runners slowed their pace going uphill and increased their pace going downhill.  The changes were largely accomplished by changing stride length, as stride frequency remained fairly constant throughout.  Going uphill, runners typically [and subconsciously] slowed their pace to keep their oxygen consumption at or near their anaerobic threshold.  Going downhill, however, runners increased pace - but did not approach their threshold levels.  This suggests that, going downhill, runners limit their speed based on other physiological factors - perhaps shock absorption or other biomechanical factors - rather than oxygen use.  Interestingly, it was observed that after each uphill or downhill section, runners took about 80 seconds to return to their level pace.

The conclusions here:

• When running downhill, it may be possible to increase speed (and save time) more than most runners imagine, if biomechanical factors can be controlled - i.e. if impact stresses can be attenuated.
• If running a little slower (than you think ideal) on uphills allows for a faster return to normal pace when terrain levels out, you may actually gain overall efficiency.

Recent research suggests that keeping the body's internal ("core") temperature down, by drinking cold (rather than warm or neutral temp) fluids, may improve exercise/athletic performance in warm conditions.  Hyperthermia is a significant factor in fatigue, as the body tends to regulate its temperature by moderating output when it gets too hot.  You can limit the effect of heat buildup by drinking ice cold fluids before AND during your race or activity.  Starting BEFORE the activity actually "pre-cools" the body, allowing greater endurance before heat builds up.  Likewise, drinking cold fluids (if available) during the event may also delay fatigue and prevent hyperthermia.